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Message-ID: <CAPDyKFrVopgySevDVZtkZdHBBxiiVNh73VOXLqaHfXs9MyiZ+w@mail.gmail.com>
Date: Mon, 28 Oct 2024 14:28:02 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Sibi Sankar <quic_sibis@...cinc.com>
Cc: sudeep.holla@....com, cristian.marussi@....com, jassisinghbrar@...il.com,
dmitry.baryshkov@...aro.org, linux-kernel@...r.kernel.org,
arm-scmi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-arm-msm@...r.kernel.org, johan@...nel.org, konradybcio@...nel.org,
linux-pm@...r.kernel.org, tstrudel@...gle.com, rafael@...nel.org,
Johan Hovold <johan+linaro@...nel.org>
Subject: Re: [PATCH V4 3/4] pmdomain: core: Fix debugfs node creation failure
On Wed, 23 Oct 2024 at 12:22, Sibi Sankar <quic_sibis@...cinc.com> wrote:
>
> The domain attributes returned by the perf protocol can end up
> reporting identical names across domains, resulting in debugfs
> node creation failure. Fix this failure by ensuring that pm domains
> get a unique name using ida in pm_genpd_init.
>
> Logs: [X1E reports 'NCC' for all its scmi perf domains]
> debugfs: Directory 'NCC' with parent 'pm_genpd' already present!
> debugfs: Directory 'NCC' with parent 'pm_genpd' already present!
>
> Reported-by: Johan Hovold <johan+linaro@...nel.org>
> Closes: https://lore.kernel.org/lkml/ZoQjAWse2YxwyRJv@hovoldconsulting.com/
> Fixes: 718072ceb211 ("PM: domains: create debugfs nodes when adding power domains")
> Suggested-by: Ulf Hansson <ulf.hansson@...aro.org>
> Signed-off-by: Sibi Sankar <quic_sibis@...cinc.com>
> ---
>
> v3:
> * Update device names only when a name collision occurs [Dmitry/Ulf]
> * Drop Johan's T-b from "fix debugfs node creation failure"
>
> drivers/pmdomain/core.c | 65 ++++++++++++++++++++++++++++++---------
> include/linux/pm_domain.h | 1 +
> 2 files changed, 51 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
> index 76490f0bf1e2..756ed0975788 100644
> --- a/drivers/pmdomain/core.c
> +++ b/drivers/pmdomain/core.c
> @@ -7,6 +7,7 @@
> #define pr_fmt(fmt) "PM: " fmt
>
> #include <linux/delay.h>
> +#include <linux/idr.h>
> #include <linux/kernel.h>
> #include <linux/io.h>
> #include <linux/platform_device.h>
> @@ -23,6 +24,9 @@
> #include <linux/cpu.h>
> #include <linux/debugfs.h>
>
> +/* Provides a unique ID for each genpd device */
> +static DEFINE_IDA(genpd_ida);
> +
> #define GENPD_RETRY_MAX_MS 250 /* Approximate */
>
> #define GENPD_DEV_CALLBACK(genpd, type, callback, dev) \
> @@ -189,7 +193,7 @@ static inline bool irq_safe_dev_in_sleep_domain(struct device *dev,
>
> if (ret)
> dev_warn_once(dev, "PM domain %s will not be powered off\n",
> - genpd->name);
> + dev_name(&genpd->dev));
>
> return ret;
> }
> @@ -274,7 +278,7 @@ static void genpd_debug_remove(struct generic_pm_domain *genpd)
> if (!genpd_debugfs_dir)
> return;
>
> - debugfs_lookup_and_remove(genpd->name, genpd_debugfs_dir);
> + debugfs_lookup_and_remove(dev_name(&genpd->dev), genpd_debugfs_dir);
> }
>
> static void genpd_update_accounting(struct generic_pm_domain *genpd)
> @@ -731,7 +735,7 @@ static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
> genpd->states[state_idx].power_on_latency_ns = elapsed_ns;
> genpd->gd->max_off_time_changed = true;
> pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
> - genpd->name, "on", elapsed_ns);
> + dev_name(&genpd->dev), "on", elapsed_ns);
>
> out:
> raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_ON, NULL);
> @@ -782,7 +786,7 @@ static int _genpd_power_off(struct generic_pm_domain *genpd, bool timed)
> genpd->states[state_idx].power_off_latency_ns = elapsed_ns;
> genpd->gd->max_off_time_changed = true;
> pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
> - genpd->name, "off", elapsed_ns);
> + dev_name(&genpd->dev), "off", elapsed_ns);
>
> out:
> raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_OFF,
> @@ -1941,7 +1945,7 @@ int dev_pm_genpd_add_notifier(struct device *dev, struct notifier_block *nb)
>
> if (ret) {
> dev_warn(dev, "failed to add notifier for PM domain %s\n",
> - genpd->name);
> + dev_name(&genpd->dev));
> return ret;
> }
>
> @@ -1988,7 +1992,7 @@ int dev_pm_genpd_remove_notifier(struct device *dev)
>
> if (ret) {
> dev_warn(dev, "failed to remove notifier for PM domain %s\n",
> - genpd->name);
> + dev_name(&genpd->dev));
> return ret;
> }
>
> @@ -2014,7 +2018,7 @@ static int genpd_add_subdomain(struct generic_pm_domain *genpd,
> */
> if (!genpd_is_irq_safe(genpd) && genpd_is_irq_safe(subdomain)) {
> WARN(1, "Parent %s of subdomain %s must be IRQ safe\n",
> - genpd->name, subdomain->name);
> + dev_name(&genpd->dev), subdomain->name);
> return -EINVAL;
> }
>
> @@ -2089,7 +2093,7 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
>
> if (!list_empty(&subdomain->parent_links) || subdomain->device_count) {
> pr_warn("%s: unable to remove subdomain %s\n",
> - genpd->name, subdomain->name);
> + dev_name(&genpd->dev), subdomain->name);
> ret = -EBUSY;
> goto out;
> }
> @@ -2199,6 +2203,23 @@ static void genpd_lock_init(struct generic_pm_domain *genpd)
> }
> }
>
> +static bool genpd_name_present(const char *name)
> +{
> + bool ret = false;
> + const struct generic_pm_domain *gpd;
> +
> + mutex_lock(&gpd_list_lock);
> + list_for_each_entry(gpd, &gpd_list, gpd_list_node) {
> + if (!strcmp(dev_name(&gpd->dev), name)) {
> + ret = true;
> + break;
> + }
> + }
> + mutex_unlock(&gpd_list_lock);
> +
> + return ret;
> +}
> +
> /**
> * pm_genpd_init - Initialize a generic I/O PM domain object.
> * @genpd: PM domain object to initialize.
> @@ -2226,6 +2247,7 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
> genpd->status = is_off ? GENPD_STATE_OFF : GENPD_STATE_ON;
> genpd->device_count = 0;
> genpd->provider = NULL;
> + genpd->device_id = -ENXIO;
> genpd->has_provider = false;
> genpd->accounting_time = ktime_get_mono_fast_ns();
> genpd->domain.ops.runtime_suspend = genpd_runtime_suspend;
> @@ -2266,7 +2288,18 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
> return ret;
>
> device_initialize(&genpd->dev);
> - dev_set_name(&genpd->dev, "%s", genpd->name);
> +
> + if (!genpd_name_present(genpd->name)) {
> + dev_set_name(&genpd->dev, "%s", genpd->name);
> + } else {
> + ret = ida_alloc(&genpd_ida, GFP_KERNEL);
> + if (ret < 0) {
> + put_device(&genpd->dev);
> + return ret;
> + }
> + genpd->device_id = ret;
> + dev_set_name(&genpd->dev, "%s_%u", genpd->name, genpd->device_id);
> + }
If we can't assume that the genpd->name is unique, I think we need to
hold the gpd_list_lock over this entire new section, until we have
added the new genpd in the gpd_list. I am not sure we really want this
as it could hurt (theoretically at least) boot/probing on systems
where a lot of genpds are being used.
That said, I would suggest we go for Dmitry's suggestion to make this
genpd provider specific. Let's add a new genpd flag that genpd
providers can set, if they need an ida to be tagged on to their
device-name. Then we should set that flag for SCMI perf/power domains.
[...]
Kind regards
Uffe
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